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Yanggu, South Korea

Kim Y.R.,Seoul National University | Kim Y.R.,Agency for Defense Development | Lee H.J.,LIGNex1 Co Ltd. | Kim S.,Seoul National University | Jeung I.-S.,Seoul National University
Proceedings of the Combustion Institute

Hydrogen is known as one of the green energy sources for fuel cells and hydrogen-fueled cars in the next generation. The storage of high-pressure hydrogen gas conditions is preferred to its storage in cryogenic liquid state. However, cases of unidentified self-ignitions were reported, notably when the high-pressure hydrogen gas suddenly leaked out. Only a few of numerical simulations have shown visually the processes of the self-ignition inside a tube. This paper presents a flow visualization study to investigate the self-ignition mechanism in a test tube i.e. how the ignition process is initiated and the flame propagates. In addition to visualization, measurement of a number of pressure and light sensors installed in the tube supported the analysis of the self-ignition and flame propagation. The test result showed that self-ignition takes place at the boundary layer behind the front center of mixing zone at first, and the flame propagates to the front of mixing zone and tail of the mixing zone along the boundary layer. It showed that self-ignition is accompanied with complex mixing induced by shock interaction with the mixing front. It is also suggested that the self-ignition boundary has a certain critical threshold of static pressure at the boundary layer, based on various burst pressures of hydrogen. © 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved. Source

Choi H.,Yonsei University | Choi K.,LIGNex1 Co Ltd. | Kim J.,Yonsei University
IEEE Transactions on Information Forensics and Security

This paper introduces a novel fingerprint matching algorithm using both ridge features and the conventional minutiae feature to increase the recognition performance against nonlinear deformation in fingerprints. The proposed ridge features are composed of four elements: ridge count, ridge length, ridge curvature direction, and ridge type. These ridge features have some advantages in that they can represent the topology information in entire ridge patterns existing between two minutiae and are not changed by nonlinear deformation of the finger. For extracting ridge features, we also define the ridge-based coordinate system in a skeletonized image. With the proposed ridge features and conventional minutiae features (minutiae type, orientation, and position), we propose a novel matching scheme using a breadth-first search to detect the matched minutiae pairs incrementally. Following that, the maximum score is computed and used as the final matching score of two fingerprints. Experiments were conducted for the FVC2002 and FVC2004 databases to compare the proposed method with the conventional minutiae-based method. The proposed method achieved higher matching scores. Thus, we conclude that the proposed ridge feature gives additional information for fingerprint matching with little increment in template size and can be used in conjunction with existing minutiae features to increase the accuracy and robustness of fingerprint recognition systems. © 2011 IEEE. Source

Jung J.,LIGNex1 Co Ltd. | Lim J.,Ajou University
IEEE Transactions on Wireless Communications

In WLAN systems, the difference in propagation delay among stations (STAs) can exceed the predefined cyclic prefix length, leading to multiple access interference (MAI). To solve this MAI problem, it is necessary to use a longer cyclic prefix length for orthogonality between different subchannels; however, this sacrifices system efficiency due to the cyclic prefix overhead. In this paper, we propose a group contention-based OFDMA to solve the MAI problem with an adequate cyclic prefix length and support a larger number of STAs. The STAs within the cyclic prefix duration that are synchronized to an access point (AP), are included in the same contending group and compete with other STAs of the group in transmitting packets. The proposed scheme allows for the adoption of an adequate cyclic prefix length without MAI, and is able to reduce the cyclic prefix overhead. In addition, since no packet errors are induced by MAI in any of the STAs, the STAs can transmit simultaneously without redundant short interframe spaces (SIFSs) and other control packets. Through analysis and simulation, we show that for a large number of STAs, the proposed scheme achieves higher throughput than 802.11 protocols and a conventional CSMA combined with OFDMA. © 2012 IEEE. Source

LIG Nex1 Co. | Date: 2010-12-22

Provided are an apparatus and a method for processing data in an ad-hoc network, particularly, an MANET. The method includes: (a) determining whether to generate any one of first data and second data having a priority lower than the first data; (b) when predetermined data is generated in accordance with the determination, measuring a mode value related to the driving of a first node which currently possesses the predetermined generated data; and (c) processing, by the first node, the generated data by considering a content of the generated data and the measured mode value.

Provided are a controlling apparatus for ejecting a guided missile and a method for ejecting the guided missile inserted into a launching tube. More particularly, The present invention provides a controlling apparatus for ejecting a guided missile additionally including a power supply controller which applies a signal for ejecting a guided weapon to a fuse during separating the fuse used for igniting a propulsion engine in the guided weapon and an ejection controlling method using the same.

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